IEEE Std. 802.1Q-2005 multiple spanning tree protocol (MSTP) is widely used in computer networks. With IEEE Std. 802.1Q-2005 MSTP, a bridged network may be organized into multiple spanning tree (MST) regions. Frames originating at one network node inside of a MST region, and destined for another network node of the same MST region, are contained inside the MST region. From the point of view of nodes outside of the MST region, MST regions appear as a single logical entity (specifically, a single virtual bridge). As a result of this, load balancing of traffic is typically not available across the boundaries of MST regions. Even if there are multiple links that interconnect a MST region with external nodes, only a single link generally may be utilized. This limitation of MST regions has proved problematic in certain network configurations. Sometimes it may be desirable to contain traffic among a particular set of network nodes and present them a single logical entity to external nodes, and also enable load balancing between the group of network nodes and external nodes. However, this is currently not possible using IEEE Std. 802.1Q-2005 MSTP.